On Tuesday morning, a tribunal of five judges at Hague-based Permanent Court of Arbitration issued a highly anticipated and unanimous award in Republic of Philippines v. People’s Republic of China, a case filed in 2013 by Manila concerning maritime entitlements and the status of features in the South China Sea, among other issues.

The Tribunal’s award is highly favorable to the Philippines, ruling that China’s nine-dash line claim and accompanying claims to historic rights have no validity under international law; that no feature in the Spratly Islands, including Taiwan-occupied Itu Aba (or Taiping Island), is an island under the United Nations Convention on the Law of the Sea (UNCLOS); and that the behavior of Chinese ships physically obstructing Philippine vessels is unlawful.

Perhaps the most significant finding–and the one most likely to disturb China–is the Tribunal’s award that China’s nine-dash line and claim to historic rights in the South China Sea are both invalid under international law. Notably:

the Tribunal concluded that, to the extent China had historic rights to resources in the waters of the South China Sea, such rights were extinguished to the extent they were incompatible with the exclusive economic zones provided for in the Convention.

Part of the Tribunal’s reasoning on historic rights considered historical evidence, concluding that while China may have made use of the islands in the South China Sea, there was no strong evidence that China “had historically exercised exclusive control over the waters or their resources.” This latter point is a particularly strong rebuttal to China’s position and its rhetoric on the South China Sea.

The Tribunal’s decision also rules that Chinese reclamation activities in the Spratly Islands, where the country has built seven artificial islands, are illegal under UNCLOS. Clarifying its reasoning for ruling Itu Aba–the largest South China Sea feature and one with a substantial Taiwanese presence–an island, the Tribunal said that under Article 121.3 of UNCLOS, the clause defining what constitutes an island, a “stable community of people” is a necessary requirement. Taiwan had submitted its case to the Tribunal for why Itu Aba should have been considered an island, claiming that the feature had the self-sufficient means necessary to sustain human life, including fresh water.

Regarding the status of features in the Spratly Islands–a key feature of the Philippines’ case against China–the Tribunal ruled that “Scarborough Shoal, Johnson Reef, Cuarteron Reef, and Fiery Cross Reef are high-tide features and that Subi Reef, Hughes Reef, Mischief Reef, and Second Thomas Shoal were submerged at high tide in their natural condition.” These designations comport with the Philippines’ original positions in its filing to the Tribunal, demonstrating that the country’s legal reasoning for why these features should be considered either high-tide features or low-tide elevations was accurate.

The Tribunal disagreed with the Philippines on the status of just two features: Gaven Reef (North) and McKennan Reef, concluding that both are high tide features. Under UNCLOS, high tide features or “rocks” are entitled to a 12 nautical mile territorial sea. Nevertheless, the Tribunal ruled certain Chinese activities in the Spratlys illegal, based on its finding that Mischief Reef, Second Thomas Shoal, and Reed Bank “form part of the exclusive economic zone and continental shelf of the Philippines.” While the Tribunal stated its opinion that these features comprised the Philippines’ lawful continental shelf under UNCLOS, it did not consider the sovereignty of individual features in the South China Sea. Questions of territorial sovereignty are outside of the scope of the UNCLOS, the international treaty forming the basis for adjudication in this case.

The Tribunal’s award also found that through its “large-scale land reclamation activities in the Spratly Islands,” China had “caused severe harm to the coral reef environment and violated its obligation to preserve and protect fragile ecosystems and the habitat of depleted, threatened, or endangered species.” The Tribunal also found that the Chinese government is aware that Chinese fishermen in the South China Sea were purposefully exploiting endangered species “on a substantial scale.”

In one area, the Tribunal found that it lacked jurisdiction. Specifically, it ruled that because a stand-off between China and the Philippines involved “military activities” it was excluded from compulsory settlement under UNCLOS.

China’s Foreign Ministry, keeping to its position announced before the award, said that the Tribunal’s award “is null and void and has no binding force.” “China neither accepts nor recognizes it,” it added, in a statement posted to Xinhua’s website.

The Philippines, despite the favorable nature of the award, has reacted carefully. According to the Philippine Star, Philippines Foreign Secretary Perfecto Yasay, Jr., said that the country’s experts are studying the award. He also noted that the country “maintains respect for the milestone decision” and “upholds international law.”

Next Steps and Analysis

Read any way, the Tribunal’s finding on the merits here is hugely favorable to the Philippines, with the decision and reasoning mostly comporting with what Manila had argued (with a few exceptions). In China, the award will make for difficult reading. It marks the first significant international legal decision on the maritime disputes in the South China Sea. The Tribunal’s findings on the nine-dash line and historic rights in particular will render Chinese language on activities in other parts of the South China Sea–including the exclusive economic zones of Vietnam and Indonesia–awkward. Though this case was borne of tensions between China and the Philippines after the Scarborough Shoal stand-off in 2012, it will come to bear on all claimants in the area.

China’s behavior in the aftermath of this decision remains uncertain. As the foreign ministry statement demonstrates, Beijing is eager to clarify that it does not accept the result of legitimacy of the Tribunal’s award and will continue its activities in the South China Sea unhindered. Additionally, there are signs that the new government in the Philippines, under the leadership of President Rodrigo Duterte, will look to forge a path to compromise, attempting to provide China with a face-saving “off ramp” after the highly embarrassing result of the award. Given the Tribunal’s award on Itu Aba notably, it’s unclear how Duterte would reasonably offer China some sort of joint development arrangement that would not then also concede waters legally deemed to be the Philippines’ per this award.

The award’s affirmation of Scarborough Shoal as a rock and Second Thomas Shoal as a low-tide elevation suggests a retrenchment of the status quo, where China can continue to occupy Scarborough and the Philippines can continue to treat BRP Sierra Madre, the grounded ship at Second Thomas Shoal, as an outpost. If China and the Philippines do pursue bilateral talks, these two features could be an area with some bargaining potential.

Another area to watch will be the upcoming meeting of the foreign ministers of the ten members of the Association of Southeast Asian Nations (ASEAN) in Vientiane, Laos. The ministers will meet starting July 21. As the recent imbroglio at the Kunming meeting between ASEAN ministers and the Chinese foreign minister revealed, fissures exist within the grouping. Given the particularly strong nature of this award, it is unlikely that ASEAN ministers will be able to offer a strong statement in support of the Tribunal. Indeed, given signs that the Philippines itself may be looking to ease on the pressure against China, there may be less interest within the regional grouping to push for a strong statement.

Whatever happens next, the nature of maritime and even territorial disputes in the South China Sea will have changed considerably. A feature on most every map of the disputes in the region–China’s ambiguous and capacious nine-dash line–has been declared illegal under international law by a Tribunal convened under the United Nations Convention on the Law of Sea. While features won’t change hands anytime soon and while artificial islands won’t turn back into their natural, pre-reclamation state as submerged reefs or partially exposed rocks, the legal understanding of these disputes will stand on momentous precedent.